U.S. patent number 4,550,044 [Application Number 06/521,125] was granted by the patent office on 1985-10-29 for ballistic resistant armor panel and method of constructing the same.
This patent grant is currently assigned to Figgie International, Inc.. Invention is credited to William K. Ansite, Isadore Rosenberg.
United States Patent |
4,550,044 |
Rosenberg , et al. |
October 29, 1985 |
Ballistic resistant armor panel and method of constructing the
same
Abstract
A ballistic resistant armor panel and a method of constructing
the same utilizes a first layer of resin-impregnated fabric, a
second layer of flexible woven fabric, a border layer of
resin-impregnated fabric bordering the second layer, and a third
layer of resin-impregnated fabric. The percentage by weight of
resin in the first layer is such that the first layer distributes
the impact of a projectile which strikes its surface over a large
area of the panel and effectively contributes to the ability of the
panel to stop and/or slow the projectile. Furthermore, the second
layer of flexible woven fabric is encapsulated by the first, border
and third layers. Such a construction minimizes blunt trauma in
body armor in which the panel is utilized and preserves the dry
ballistic resistance of the woven fabric comprising the second
layer. The panel of the invention is particularly well-suited for
utilization in a helmet, and a helmet which includes such a panel
possesses very good ballistic resistance.
Inventors: |
Rosenberg; Isadore (Downey,
CA), Ansite; William K. (Glendale, CA) |
Assignee: |
Figgie International, Inc.
(Willoughby, OH)
|
Family
ID: |
24075470 |
Appl.
No.: |
06/521,125 |
Filed: |
August 8, 1983 |
Current U.S.
Class: |
428/101; 428/192;
428/323; 428/911; 156/290; 428/193; 428/408 |
Current CPC
Class: |
B32B
19/06 (20130101); F41H 1/08 (20130101); A42B
3/063 (20130101); B32B 5/024 (20130101); B32B
5/26 (20130101); B32B 38/08 (20130101); F41H
5/0485 (20130101); Y10T 428/24777 (20150115); Y10S
428/911 (20130101); Y10T 428/25 (20150115); Y10T
428/30 (20150115); Y10T 428/24785 (20150115); Y10T
428/24025 (20150115); B32B 2260/046 (20130101); B32B
2262/106 (20130101); B32B 2262/0269 (20130101); B32B
2260/023 (20130101); B32B 2607/00 (20130101); B32B
2571/02 (20130101); B32B 2264/102 (20130101); B32B
2262/101 (20130101) |
Current International
Class: |
B32B
19/00 (20060101); B32B 19/06 (20060101); F41H
5/04 (20060101); F41H 5/00 (20060101); B32B
003/06 () |
Field of
Search: |
;428/251,252,408,911,287,192,193,284,283,323,101,240,242,246
;156/290 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bell; James J.
Attorney, Agent or Firm: Christel, Bean & Linihan
Claims
We claim:
1. A ballistic resistant panel comprising:
a first layer including a plurality of plies of resin-impregnated
fabric;
a second layer including at least one ply of flexible woven fabric
supported adjacent said first layer; and
a third layer including at least one ply of resin-impregnated
fabric supported adjacent said second layer opposite said first
layer, said second layer being smaller in area than said first and
third layers, said first and third layers each having a central
portion and a marginal portion which borders said central portion,
said second layer being positioned between said central portions of
said first and third layers and said marginal portions being bonded
together whereby said second layer is encapsulated between said
first and third layers.
2. A ballistic resistant panel as defined in claim 1 wherein the
resin of said resin-impregnated fabric of at least one of said
first and third layers includes a small amount of titanium
dioxide.
3. A ballistic resistant panel as defined in claim 1 wherein the
percentage by weight of titanium dioxide in the resin of said
layers including titanium dioxide is about one percent.
4. A ballistic resistant panel as defined in claim 1 wherein said
flexible woven fabric is woven of a ballistic-resistant material
which must be protected from a wet environment to maintain its
ballistic resistant characteristics.
5. A ballistic resistant panel as defined in claim 1 wherein said
flexible woven fabric is woven of an aramid fiber.
6. A ballistic resistant panel as defined in claim 1 further
comprising:
a border layer including at least one ply of resin-impregnated
fabric positioned and bonded between said marginal portions of said
first and third layers whereby said first layer, border layer and
third layer collectively encapsulate said second layer.
7. A ballistic resistant panel comprising:
a first layer including a plurality of plies of resin-impregnated
fabric and having a first central portion and a first marginal
portion, said marginal portion bordering said first central
portion;
a second layer including at least one ply of flexible woven fabric
adjacent said first central portion; and
a third layer including at least one ply of resin-impregnated
fabric and having a second central portion and a second marginal
portion, said second marginal portion bordering said second central
portion, said third layer adjacent the side of said second layer
opposite said first layer, said second layer positioned between
said first central portion and said second central portion, and
said first and second marginal portions being bonded together
whereby said second layer is encapsulated between said first layer
and said third layer.
8. A ballistic resistant panel as defined in claim 7 further
comprising a border layer including at least one ply of
resin-impregnated fabric positioned between said first and second
marginal portions and extending therealong, said border layer being
bonded on one side to said first marginal portion and being bonded
on another side to said second marginal portion so that said first
layer, border layer and third layer collectively encapsulate said
second layer.
9. A ballistic resistant panel as defined in claim 7 wherein said
flexible woven fabric is woven of an aramid fiber.
10. A method of constructing a ballistic resistant panel comprising
the steps of:
providing a first layer including a plurality of plies of
resin-impregnated fabric and having a first central portion and a
first marginal portion, said first marginal portion bordering said
first central portion;
providing a second layer including at least one ply of flexible
woven fabric;
providing a third layer including at least one ply of
resin-impregnated fabric and having a first central portion and a
first marginal portion, said second marginal portion bordering said
second central portion;
spreading said second layer in overlying relationship with said
second central portion of said third layer;
spreading said first layer in overlying relationship with said
second layer and said third layer so that said first central
portion overlies said second layer; and
bonding said first and second marginal portions together so that
said second layer is encapsulated between said first layer and said
third layer.
11. A method as defined in claim 10 wherein the step of spreading
said second layer in overlying relationship with said third layer
is followed by the steps of:
providing a border layer including at least one narrow ply of
resin-impregnated fabric; and
spreading said border layer in overlying relationship with said
second marginal portion so that said border layer is positioned
between the edge of said second layer and the edge of said third
layer, and wherein the step of spreading said first layer in
overlying relationship with said second and third layers positions
said border layer between said first and second marginal portions
and the step of bonding said first and second marginal portions
together bonds said border layer therebetween.
12. A method as defined in claim 10 wherein the step of bonding
comprises:
heating said first and second marginal portions; and pressing said
marginal portions together.
13. A method as defined in claim 10 wherein said resin-impregnated
fabric of said first layer includes such a composition of resin and
fabric that the impact of a projectile which strikes its surface is
distributed over a large area of said first layer and effective
ballistic resistance is provided by said first layer.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to ballistic resistant armor and
relates, more particularly, to an improved panel structure for such
armor.
As body armor dissipates the energy of a projectile, such as a
bullet or a piece of shrapnel, which strikes its surface, much of
the impact of the projectile upon the armor is transferred to the
wearer of the armor. The effect upon the wearer of this transferred
impact is referred to as blunt trauma. If severe, blunt trauma can
render the wearer stunned or unconscious. It is therefore desirable
that when a projectile strikes body armor, the blunt trauma is
minimized.
It is believed that the severity of blunt trauma depends, at least
in part, upon the size of the area of the armor over which the
impact of the projectile is distributed. More specifically, the
larger or broader the area of the armor over which the impact of a
projectile is distributed, the less the blunt trauma. Therefore, in
order that blunt trauma be minimized, the area of the armor over
which the impact of a projectile is distributed should be
large.
The size of the area over which the impact of a projectile is
distributed is believed to be dependant upon the rigidity of the
armor. In other words, the more rigid the armor, the larger the
area over which the impact of the projectile is distributed. Thus,
the more rigid the armor, the less the blunt trauma.
A layer of an armor panel comprised of various conventional
ballistic resistant materials can be rigidly constructed by
blending a resin binder with the materials which comprise the
layer. For example, it is described in U.S. Pat. No. 3,722,355 that
an armor layer comprised of fabric woven of glass and nylon fibers
and which is flexible without a binding resin becomes rigid and
semi-structural with a binding resin. It has been discovered,
however, that the ballistic resistance, or the ability to stop
and/or slow projectiles, of such an armor layer decreases as its
degree of rigidity is increased. Therefore, if it is desired that
the armor layer comprised of various conventional ballistic
materials contributes to the ballistic resistance of the armor, the
degree of rigidity of the armor layer is limited.
Because of its ballistic resistance, a strong and durable fabric
woven of a special aramid fiber of the type or equivalent to the
type marketed by E. I. Du Pont de Nemours & Company under the
tradename Kevlar is commonly utilized in lightweight ballistic
resistant body armor and supported within such armor in layers. It
has been discovered, however, that woven fabric of the
aforedescribed type loses some of its ballistic resistance when it
becomes wet. Yet, body armor in which layers of this woven fabric
is used is commonly expected to be worn during a rainstorm,
contacted by body perspiration, or otherwise exposed to a wet
environment during its service life. If such armor does not protect
its layers of woven fabric from becoming wet when the armor itself
becomes wet, the effectiveness of the armor as a body-protecting
shield can be seriously reduced.
It is an object of the present invention to provide an improved
ballistic resistant panel which both minimizes blunt trauma and
provides effective ballistic resistance, and a method of
constructing the improved panel.
Another object of the present invention is to provide such a panel
which is highly effective in slowing and/or stopping projectiles
which impinge upon its surface.
Still another object of the present invention is to provide such a
panel which is relatively light in weight.
Yet still another object of the present invention is to provide
such a panel including woven fabric of the aforedescribed type and
a method of constructing the same wherein the woven fabric is
protected from becoming wet during the life of the panel.
A further object of the present invention is to provide such a
panel which has a surface that is well-suited for finishing
operations, such as sanding or painting, and requires no priming
before an outside layer of paint is applied.
A still further object of the present invention is to provide such
a panel which is particularly well-suited for utilization in a
ballistic resistant helmet.
SUMMARY OF THE INVENTION
The present invention resides in an improved panel structure for
ballistic resistant body armor and a method of constructing the
improved panel.
The panel of the invention includes a layup of resin-impregnated
fabric comprised of such a composition of resin and fabric that the
impact of a projectile which strikes its surface is distributed
over a large area of the panel while the panel provides effective
ballistic resistance.
In another embodiment of the panel of the invention, the layup of
resin-impregnated fabric, as aforedescribed, is a first layer and
the panel further includes a second layer supported adjacent the
first layer. The second layer includes at least one ply of flexible
woven fabric.
In a further embodiment of the panel of this invention, the panel
includes a first and second layer as in the aforedescribed another
embodiment and further includes a third layer of resin-impregnated
fabric supported adjacent the side of the second layer opposite the
first layer. The first and third layers each define a central
portion and a marginal portion bordering the central portion, and
the second layer is positioned between the central portions of the
first and third layers. The marginal portions of the first and
third layers are bonded together so that that second layer is
completely encapsulated between the first and third layers.
The method of the invention includes the steps of constructing
various embodiments of the panel of the invention. The
aforedescribed another embodiment is constructed by placing the
first layer in overlying relationship with the second layer and
suitably attaching the layers together. During the construction of
the aforedescribed further embodiment, the second layer is spread
over the third layer so that it overlies the central portion
thereof. The first layer is then spread over the second and third
layers so that its central portion overlies the second layer and
its marginal portion overlies the marginal portion of the third
layer. The marginal portions are then bonded together so that the
second layer is completely encapsulated by the first and third
layers.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of a ballistic resistant
armor panel comprising one embodiment of the present invention.
FIG. 2 is a perspective view of the assembled FIG. 1 armor
panel.
FIG. 3 is an elevational view of a helmet, shown partially
cut-away, in which a panel comprising another embodiment of the
present invention is included.
FIG. 4 is a view of a cut-away portion of the FIG. 3 helmet, drawn
to a slightly larger scale.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning now to the drawings in greater detail, there is shown in
FIGS. 1 and 2 a ballistic resistant panel, generally indicated 10,
comprising one embodiment of the present invention. The panel 10 is
comprised of a first layer 12 of resin-impregnated fabric, a second
layer 14 of flexible woven fabric, a border layer 15 of
resin-impregnated fabric, and a third layer 16 of resin-impregnated
fabric. The first layer 12 is of such a composition of resin and
fabric that it distributes or disperses the impact of a projectile
which strikes its surface over a large area of the panel 10 and
effectively contributes to the ballistic resistance of the panel
10. The second layer 14 of flexible woven fabric is encapsulated by
the first, third and border layers.
The panel 10 is worn by a user so that the first layer 12 provides
the outermost layer of panel protection from bullets or similar
projectiles. For this reason, the first layer 12 of the panel 10
can be appropriately referred to as the front or outer layer of the
panel. Defined by the first layer 12 on the side of the first layer
opposite the second layer 14 is the front surface 18 of the panel
10.
With reference to FIG. 1, the first layer 12 is comprised of three
plies of a relatively rigid, resin-impregnated fabric. Included in
the first layer 12 is a central portion 24 and a marginal portion
26 which borders the central portion 24. The three plies of the
first layer 12 are arranged in layup fashion and are uniformly
impregnated with resin. In addition, the first layer 12 is
waterproof so that no moisture is permitted to enter the second
layer 14 of flexible woven fabric through the front surface 18 of
the panel 10. The fabric of each ply of the first layer 12 is
chosen from the group consisting of glass fabric, graphite fabric
and carbon fabric, and the resin with which the fabric is
impregnated is one of a number of suitable resins, such as a
vinylester, polyester, or phenolformaldehyde resin. With regard to
the choice of resin in the resin-impregnated fabric, however, it
will be understood that armor in which the panel 10 is included is
commonly expected to withstand a decontamination process in which
the armor is submerged in boiling water. Therefore, the resin with
which the fabric of the first layer 12 is impregnated should not
degrade or soften when exposed to temperatures at or about
212.degree. F. (100.degree. C.).
The composition of the first layer 12 provides a front finishing
operations, such as sanding or painting. If the fabric of the first
layer is impregnated with a resin which includes a small amount of
titanium dioxide mixed therein, paint adheres to the front layer in
such a manner that any need for a coat of priming before an outside
layer of paint is applied is obviated. It has been found that a
mixture of any of the aforedescribed resins with an amount of
titanium dioxide equivalent to about one percent by weight of the
total mixture provides a resulting resin composition with suitable
paintadhering qualities and does not adversely effect the ballistic
characteristics of the first layer.
The second layer 14 includes eight plies, arranged in layup
fashion, of a flexible fabric woven of an aramid fiber of the type
or equivalent to the type produced by E.I. Du Pont de Nemours &
Company under the tradename Kevlar. Kevlar fibers are produced and
sold by Du Pont in the form of roving and yarns of various Denier
and are capable of being woven into any of a number of various
weaves. It has been found that a plain weave fabric constructed of
1000 or 1500 Denier yarn provides the plies of the second layer
with satisfactory ballistic resistance.
The border layer 15 includes six plies of a relatively rigid,
resin-impregnated fabric. The fabric within each ply of the border
layer 15 can be any of a number of suitable fabrics, such as glass
fabric, graphite fabric or carbon fabric, and the resin with which
each ply of the border layer is impregnated can be any of a number
of suitable resins, such as a polyester resin. Each ply of the
border layer is in the shape of a rectangular frame and spread in
overlying relationship with one another. The opening, indicated 17,
defined by the border layer 15 nestingly accepts the second layer
14. The thickness of the border layer 15 is generally the same as
that of the second layer 14, and the border layer 15 is
waterproof.
The third layer 16 includes a single ply of a relatively rigid,
resin-impregnated fabric. Included in the third layer is a central
portion 32 and a marginal portion 34 which borders the central
portion 32. The third layer 16 is waterproof so that it provides a
waterproof back layer of the panel 10. The fabric of the third
layer can be any of a number of suitable fabrics, such as glass
fabric, graphite fabric or carbon fabric, and the resin with which
the fabric of the third layer is impregnated can be any of a number
of suitable resins, such as a polyester resin. As discussed above,
however, with regard to the choice of resin of the first layer 12,
the resin with which the fabric of the third layer 16 is
impregnated should not degrade or soften when exposed to
temperatures at or about 212.degree. F. (100.degree. C.). The
composition of the third layer 16 provides a surface 30, or a lower
surface as shown, which is well-suited for panel finishing
operations, such as sanding or painting. Furthermore and as
discussed above with regard to the first layer, if a small amount
of titanium dioxide is mixed into the resin and then the fabric of
the third layer is impregnated therewith, the third layer does not
require a coat of priming before an outside layer of paint is
applied.
In accordance with the panel 10 of the present invention and with
reference to FIG. 2, the first layer 12 is comprised of such a
composition of resin and fabric that the first layer 12 distributes
the impact of a projectile which strikes its surface over a large
area of the first layer 12 and effectively resists penetration by
the projectile. To this end, various resins have been found to be
well-suited for impregnating the various fabrics of which the first
layer 12 can be comprised, and the resin composition by weight in
suitable fiber/resin combinations comprising the first layer 12 has
been determined. More specifically, if the fabric of the first
layer 12 is glass fabric, the resin with which the fabric is
impregnated can be either a vinylester resin or a polyester resin,
and the percentage by weight of resin in the composition of the
first layer is in the range of about 20 to 25 percent. If the
fabric of the first layer 12 is graphite fabric, the resin with
which the fabric is impregnated can be either a polyester resin or
a phenol-formaldehyde resin, and the percentage by weight of resin
in the composition of the first layer is in the range of about 18
to 23 percent. If the fabric of the first layer 12 is carbon
fabric, the resin with which the fabric is impregnated can be a
polyester resin, and the percentage by weight of the polyester
resin in the composition of the first layer is in the range of
about 18 to 23 percent.
It is believed that the capacity of the first layer 12 to perform
the tasks of distributing the impact of a projectile over a large
area and effectively resisting the penetration of a projectile is
due, at least in part, to the degree of rigidity of the first layer
12, and each of the aforementioned suitable compositions of fabric
and resin in the first layer 12 provides the first layer with a
degree of rigidity to effectuate these tasks.
The second layer 14 of flexible woven fabric is positioned within
the opening of the border layer 15 and sandwiched between the
central portions 24 and 32 of the first and third layers 12 and 16,
respectively. The first layer 12, border layer 15 and third layer
16 are positioned relative to one another so that the border layer
15 overlies the marginal portion 34 of the third layer 16 and the
marginal portion 26 of the first layer 12 overlies the border layer
15.
In accordance with the panel of this invention, the border layer 15
and the marginal portions 26 and 34 of the first and third layers
12 and 16, respectively, are bonded together to form a waterproof
seal along the edge of the panel 10. It follows from the above that
the first layer 12, border layer 15 and third layer 16 completely
encapsulate the second layer 14 of flexible woven fabric and
thereby protect the second layer 14 from a service or
decontamination environment which could otherwise wet the plies of
woven fabric and thereby reduce the ballistic resistance of the
second layer 14.
When a projectile strikes the front surface 18 of the panel 10, the
first layer 12 distributes the impact of the projectile over a
large area of the panel 10 and thereby minimizes the blunt trauma
in body armor in which the panel 10 is utilized. An additional
advantage provided by the structure of the panel 10 relates to the
backface signature, hereinafter defined, produced by a projectile
which strikes body armor in which the panel 10 is used.
Backface signature in body armor refers to the protuberance defined
in the inner surface of the armor caused by a projectile which
strikes the armor. lf such a protuberance is permitted to strike
the body of a wearer, injury can result. Thick layers of padding
can be placed between the inner surface of the armor and the body
of the wearer to protect the wearer from such a protuberance, but
thick layers of padding are undesirable in that they contribute to
the bulkiness and weight of the wearer's protective system. It is
believed that the chances of injury to the wearer of body armor by
backface signature are reduced as the backface signature is
blunted. In other words, injury to a wearer is less likely to
result from a protuberance which is short in length and spread over
a broad area than one which is long in length and sharp. The
backface signature produced by a projectile which strikes the panel
10 is short in depth and spread over a broad area. Therefore the
chances of injury from backface signature to a wearer of body armor
in which the panel 10 is used is minimized.
The method of the present invention includes the steps involved in
constructing the panel 10. Firstly, the third layer 16 is provided
and is placed in spread condition. The second layer 14 is then
spread over the third layer 16 so as to overlie the central portion
32 of the third layer 16. The border layer 15 is then placed upon
the marginal portion 34 of the third layer 16 so that the second
layer 14 is positioned within its opening 17. The first layer 12 is
then placed over the second layer 14 and the border layer 15 so
that its central portion 24 overlies the second layer 14 and its
marginal portion 26 overlies the border layer 15. The marginal
portions 26 and 34 and border layer 15 are thereafter bonded
together by the application of heat and pressure to the marginal
portions. The applied heat softens the resin within the marginal
portions 26 and 34 and border layer, and the applied pressure joins
the softened resin of the marginal portions 26 and 34 and border
layer 15. A watertight seal is thereby formed between the marginal
portion 26 and the border layer 15 and between the border layer 15
and marginal portion 34.
For ease of fabrication of the panel 10, it may be desirable to
bond the marginal portions 26 and 34 and border layer 15 by
applying heat and pressure over the entire area of the panel. It
has been found, however, that if this is done, a small amount of
the resin within the first layer 12 and the third layer 16 migrates
or bleeds into the second layer 14. Therefore, if the marginal
portions 26 and 34 are bonded by the application of heat and
pressure over the entire area of the panel 10, it is desirable to
provide, prior to this bonding process, plies of the first and
third layers having a percentage composition by weight of resin
which is slightly greater than the desired percentage composition
by weight of resin in the completed panel 10 to compensate for the
small amount of resin which leaves the first and third layers
during such a bonding process.
Referring to FIGS. 3 and 4, there is shown a ballastic resistant
helmet 40 in which a panel structure or system in accordance with
the present invention is incorporated. The helmet 40 is comprised
basically of a shell portion 42 and an adjustable band or strap
type head engaging means (not shown) supported within the shell
portion 42. The shell portion 42 is substantially semi-spherical in
shape and is of such size that when worn by a user, the helmet
protects a substantial portion of the user's head from injury by
bullets, shrapnel or similar projectiles. The strap type head
engaging means of the helmet is fastened against the interior of
the shell portion 42 in a manner well-known in the art and provides
the means by which the helmet is worn comfortably by the user.
The shell portion 42 of the helmet 40 is comprised of a layered
panel structure including an outer, or first, layer 44, a core, or
second, layer 46 and an inner, or third, layer 48. The inner layer
48 includes a single semi-spherical shaped ply 50 of a relatively
rigid, resin-impregnated fabric. The fabric of the inner layer 48
can be any of a number of suitable fabrics, such as glass fabric,
graphite fabric or carbon fabric, and the resin of the inner layer
48 can be any of a number of suitable resins, such as a polyester
resin. The ply of fabric of the inner layer 48 of FIGS. 3 and 4
includes a central portion 54 and a marginal portion 56. For
purposes of illustration, there is shown in FIG. 4 a dotted line 60
at which the marginal portion 54 and central portion 56 of the FIG.
3 a dotted line 52 along which the border of the marginal portion
54 and central portion generally follow. Furthermore, the marginal
portion 56 extends from the boundary of the central portion 54 to
the lower edge, indicated 58, of the helmet 40. The inner layer 48
defines a smooth inner surface, indicated 59, of the helmet shell
portion 42 and is well-suited for finishing operations, such as
sanding or painting.
The core layer 46 of the helmet shell portion 42 includes four
plies of a flexible fabric woven of an aramid fiber, discussed
above with regard to the second layer 14 of the panel 10 of FIGS. 1
and 2, and overlies the central portion 54 of the inner layer 48 so
that its edge generally follows alongside the border of the central
portion 54 and the marginal portion 56 of the inner layer 48 and,
thus, along the dotted line 52 shown in FIG. 3.
Also included in the helmet shell portion 42 is a border layer 61
comprised of a layup of two narrow plies 62,62 of resin-impregnated
fabric positioned in overlying relationship with the marginal
portion 56 of the inner layer 48 and which extends therealong
between the edge of the core layer 46 and the lower edge 58 of the
helmet 40. The fabric in each ply of the border layer 61 can be any
number of suitable fabrics, such as graphite fabric, glass fabric
or carbon fabric, and the resin in each ply of the border layer 61
can be any of a number of suitable resins, such as a polyester
resin. The border layer 61 thickens the region of the helmet shell
portion 42 between the edge of the core layer 46 and the lower edge
58 of the helmet so that this region is at least as thick as any
other region of the helmet 40.
The outer layer 44 includes two plies 68,68 of a relatively rigid
resin-impregnated fabric and includes a central portion 70 and a
marginal portion 72. The fabric within each ply of the outer layer
44 is chosen from the group consisting of glass fabric, graphite
fabric and carbon fabric, and the resin with which the fabric of
the outer layer 44 is impregnated is any of a number of suitable
resins, such as a vinylester, polyester, or phenolformaldehyde
resin. The outer layer 44 of the helmet shell portion 42
distributes the impact of a projectile over a broad area of the
helmet 40 and effectively contributes to the ballistic resistance
of the helmet 40. Accordingly, the suitable fiber/resin
combinations listed above in regard to the plies of the first layer
12 of the panel 10 of FIGS. 1 and 2 are suitable combinations of
fiber and resin of each ply of the outer layer 44, and the
percentage composition by weight of resin in each of the suitable
fiber/resin combinations set forth above in regard to the
composition of the first layer 12 applies here to the outer layer
44. The composition of the outer layer 44 provides an outer surface
of the helmet shell portion 42 which is wellsuited for finishing
operations, such as sanding or painting.
For purposes of illustration, there is shown in FIG. 4 a dotted
line 63 at which the central portion 70 and marginal portion 72 of
the outer layer 44 border one another. The border between the
central portion 70 and marginal portion 72 generally follows along
the dotted line 52 of FIG. 3. Furthermore, the marginal portion 72
extends from the boundary of the central portion 70 to the lower
edge 58 of the helmet 40. The outer layer 44 overlies the core
layer 46 and the border layer 61 so that the core layer 46 is
positioned between the central portions 54 and 70 of the inner and
outer layers 48 and 44, respectively, and so that the border layer
61 is positioned between the marginal portions 56 and 72 of the
inner and outer layers 48 and 44, respectively.
The border layer 61, the marginal portion 56 of the inner layer 48
and the marginal portion 72 of the outer layer 44, are bonded
together by the application of heat and pressure applied to the
marginal portions. The applied heat softens the resin within the
border layer 61 and the marginal portions 56,72, and the applied
pressure joins the heat-softened resin of the marginal portions and
border layer. A watertight seal is thereby formed along the lower
edge 58 of the helmet 40. It follows from the above that the core
layer 46 is encapsulated by the inner layer 48, border layer 61 and
outer layer 44 and is thereby protected from a service or
decontamination environment which could otherwise wet the woven
fabric within the core layer 46.
To construct the shell portion 42 of the helmet 40, the inner layer
48, being substantially semi-spherical in shape, is provided. The
core layer 46 is then placed over the inner layer 48 so as to
overlie the central portion 54 of the inner layer 48. The border
layer 61 is then placed over and along the marginal portion 56 of
the inner layer 48. The outer layer 44, being substantially
semi-spherical in shape, is thereafter placed over the core layer
46 and border layer 61 so that its central portion 70 overlies the
core layer 46 and its marginal portion 72 overlies the border layer
61. Heat and pressure are then applied to the marginal portions 56
and 72 of the inner and outer layers 48 and 44, respectively, so
that the border layer 61 and the marginal portions 56 and 72 bond
with one another and thereby form a watertight seal
therebetween.
An illustrative process of bonding the marginal portions 56 and 72
and border layer 61 together is initiated by placing the assembled
layers of the helmet shell portion 42 into a heated metal-surfaced
mold with the outer layer 44 engaging the surface of the mold. The
mold surface is in the shape of the outer shape of the helmet shell
portion 42 and is maintained at about 265.degree. F.-285.degree. F.
(129.degree. C.-141.degree. C.). An inflatable rubber bag is then
placed inside the helmet and inflated to about 25 pounds per square
inch so that the bag presses the helmet against the heated surface
of the mold. It has been found that when exposed to heat and
pressure under conditions as aforedescribed, the marginal portions
56 and 72 and border layer 61 are suitably bonded in about seven to
fourteen minutes.
The ballistic resistance of the helmet 40 is sufficient to defeat
many conventional small arms projectiles.
It will be understood that numerous modifications can be had to the
aforedescribed embodiments without departing from the spirit of the
invention. For example, although the shell portion 42 of the helmet
40 of FIGS. 3 and 4 has been described as including layers which
each have a stated number of plies, a helmet shell portion in
accordance with the panel of the present invention can include
layers which have an alternative number of plies. A helmet shell
portion comprised of a first, or outer layer having three plies of
resin-impregnated fabric, a second, or core layer having eight
plies of woven fabric, a border layer having three plies of
resin-impregnated fabric, and a third, or inner layer having one
ply of resin-impregnated fabric is in accordance with this
invention as well, and, like the helmet shell portion 42, can
defeat many conventional small arms projectiles.
Furthermore, although the panel of the present invention can be
used to form the shell portion of a helmet, as discussed above with
regard to the helmet 40 of FIGS. 3 and 4, the panel can also be
used to form a bullet-proof vest or any structure requiring
ballastic penetration resistance Accordingly, the descriptions
contained herein are intended as illustration and not as
limitation.
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